TORONTO — When Dallas businessman Abraham Zapruder set up his Bell and Howell home movie camera to film President Kennedy’s visit, he had no idea he would capture the most examined piece of film footage in human history.

In the 26.8 seconds of footage, Zapruder captured the passing motorcade and then the deadly shot to the president’s head, which happened right in front of his camera.

Abraham Zapruder was never the same after that.

Paul Giamatti plays the unlikely documentarian in the new film “Parkland,” which opened in limited release on Friday as November’s 50th anniversary of the assassination approaches. The film recounts the chaotic events that occurred in and around Parkland Hospital after the president was brought there with hopes of saving his life.

One of the film’s plot threads centers around the Secret Service investigation, which leads to Zapruder’s 8mm film.

“His eyes literally see the thing,” Giamatti says of Zapruder’s film.

We learn that Zapruder and the Secret Service scrambled around Dallas to find someone that knew how to process the film, as well as the fickle nature of the amateur format (it’s actually 16mm film that exposes half the frame on each side). After the film is processed, there’s some earlier family footage captured before the historical sequence from Dealey Plaza.

In an interview at the recent Toronto Film Festival, Giamatti said he felt a great deal of sympathy toward Zapruder, and he saw the essence of portraying the immigrant garment manufacturer was to channel how haunted he was by the ordeal.

“He’s this kind of inadvertent witness of the whole thing that I think he felt guilty about filming this thing, witnessing it the way he did. He felt shame and guilt and things like that. You weren’t supposed to see this and he made everybody see it,” Giamatti said.

But playing him wasn’t that easy because Zapruder was not well-known enough in public to easily understand his mannerisms.

“He’s not known as a person so I have a lot of latitude because nobody knows. But it’s a good opportunity. It’s a fun role to be able to do that,” Giamatti said.

He added: “I definitely felt a certain pressure, a certain responsibility that I’d never felt before to the guy because he really was not a man asking for any of this crap in his life.”

The Zapruder film has contributed to much speculation.

“I always think conspiracy theories are more comforting to people. It explains and gives it a narrative whereas if you let it sit, it doesn’t make any sense ... It’s definitely more than a murder mystery. It’s for a lot of people who are into the conspiracy stuff. It’s saying something about a kind of moral rot in the country,” Giamatti said.

Based on the book “Four Days in November: The Assassination of John F. Kennedy,” the film weaves the perspective stories of ordinary citizens, including the unlikely predecessor to what we know today as viral video.

“The Zapruder film was the beginning of what we think of almost as social media, you know, when imagery goes viral it takes on a meaning that transcends itself,” said “Parkland” director Peter Landesman.

“The Zapruder film has been probably the most examined piece of footage in human history, and used and abused and used to come up with all sorts of crazy conspiracies. And really, it’s the accidental home movie of a man who shouldn’t have even been there,” Landesman said.

The film also stars Billy Bob Thornton, Marcia Gay Harden and Zac Efron.